JP2005290902A - Emergency turning braking method and device for working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To rapidly stop turning in an emergency and to prevent the damage of a mechanical brake. <P>SOLUTION: A turning body is driven to turn by a permanent magnet type turning motor 17. In the emergency due to the occurrence of abnormality of a driving system or a control system of the turning motor 17, electric power generated to the motor 17 by inertial rotation is consumed by an external braking resistance 24 to perform electric brake action, and when the turning speed of the turning body is lowered to a set value or less, the mechanical brake 21 is operated to stop turning and to hold stop. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to an emergency turning braking method and apparatus for braking a turning body in an emergency in the event of an abnormality such as a power interruption of a drive system of a turning motor or a down of a control system in a working machine that drives a turning body by an electric motor. Is.

  In a swivel working machine such as an excavator or a crane, a technique using an electric motor as a swivel drive source instead of the conventional hydraulic motor is known (see Patent Document 1).

In this turning drive system using an electric motor, the electric motor is operated as a generator, and the revolving braking torque is used to brake and stop the turning body.
Japanese Patent Laid-Open No. 2001-207478

  However, in the conventional motor drive system, when an abnormality occurs such as the turning motor power being cut off due to a failure of the generator or the turning control system being down and the turning motor being unable to be controlled, the power generation action of the motor There is a situation in which braking due to is not performed, and only inertia is in a working state, which is similar to neutral free in the hydraulic system, and does not stop easily.

  On the other hand, excavators and cranes are equipped with a mechanical brake that works as a parking brake for holding a stop when the vehicle is stopped. Therefore, it is conceivable to operate this mechanical brake as an emergency brake.

  However, since the mechanical brake originally has only the braking performance designed for holding the stop, if it is operated during high-speed turning, the heat capacity may be insufficient and may be damaged. Note that if the mechanical brake has a sufficient heat capacity, the entire brake becomes large, for example, a cooling device is required, which makes it difficult to realize in terms of installation space and cost.

  Therefore, the present invention provides an emergency turning braking method and apparatus for a work machine that can promptly decelerate and stop turning in an emergency and can prevent damage to a mechanical brake.

  The invention (method) of claim 1 uses a permanent magnet type motor as a turning motor for driving the turning body to turn, and in an emergency, consumes electric power generated in the turning motor by inertial rotation by a braking resistance outside the motor. An electric brake action is performed, and the electric brake action is used to brake and decelerate the swivel body, and to activate the mechanical brake at the end of the deceleration.

  The invention (apparatus) of claim 2 is a turning electric motor that drives the turning body to turn, a mechanical brake that mechanically brakes the turning electric motor, a control means that controls the operation of the turning electric motor and the mechanical brake, and a turning speed. A permanent magnet type motor that performs an electric brake action by consuming electric power generated by inertial rotation with a braking resistor outside the motor. In the event of an emergency, an electric brake action is applied to the turning electric motor, and the mechanical brake is operated based on a speed signal from the speed detecting means when the turning speed of the turning body decreases below a set value due to the electric brake action. It is comprised as follows.

  According to a third aspect of the present invention, in the configuration of the second aspect, a hydraulic negative brake that releases a braking force when hydraulic pressure is introduced via a switching valve is used as the mechanical brake, and the control means is the switching valve. It is comprised so that the action | operation of may be controlled.

  According to a fourth aspect of the present invention, in the configuration of the second or third aspect, the speed detection means includes a comparison unit that compares a voltage or current generated by the power generation action of the swing motor with a set value. Based on this, the mechanical brake is operated.

  According to a fifth aspect of the present invention, in the configuration of the second or third aspect, a speed sensor that detects a rotational speed of the turning electric motor or a speed reduction mechanism thereof is used as the speed detecting means.

  According to a sixth aspect of the present invention, in the configuration of any one of the second to fifth aspects, the maximum torque due to the electric brake action of the turning electric motor is set to a value substantially equal to the normal motor maximum braking torque.

  According to the present invention, a permanent magnet motor that exhibits an electric brake function by consuming electric power generated by inertial rotation with an external braking resistor is used as a swing motor. The brake is decelerated and the mechanical brake is operated to stop and stop at the end of the deceleration (when the vehicle is slowed down or stopped), so that the turning body can turn quickly even when the drive system or control system is abnormal. Can be stopped.

  In addition, since the mechanical brake is operated at a low speed or a stop state at the end of deceleration, there is no possibility of damage even if the one originally installed in the machine (for example, the negative hydraulic brake of claim 3) is used as it is. Or, even if the performance of the brake is increased, it is small and does not need to be large with a large cooling device.

  By the way, the electric brake action depends on the inertial rotation speed of the revolving structure, and the generated electric power (braking force) decreases as the speed decreases.

  The invention of claim 4 pays attention to this point, and compares the voltage or current due to the power generation action of the swing motor with the set value in the comparison unit and operates the mechanical brake based on the comparison result. There is no need to provide a speed sensor for taking the operation timing of the mechanical brake. For this reason, the cost can be reduced, and the possibility of occurrence of a failure or abnormality is reduced as compared with an external sensor.

  According to the invention of claim 5, although a speed sensor is separately required, speed detection itself can be easily performed.

  According to the invention of claim 6, since the maximum torque of the electric brake (torque at the time when deceleration is started from the maximum speed) is set to a value substantially equal to the maximum braking torque of the motor at normal time, In this case, it is possible to secure a value close to normal with respect to the time and distance (angle) until turning stop, while avoiding excessive torque from acting on.

  FIG. 1 shows an excavator to be applied.

  In the figure, reference numeral 1 denotes a crawler-type lower traveling body, and an upper swing body 2 is mounted on the lower traveling body 1 so as to be rotatable about a vertical axis. A boom 3, an arm 4, a bucket is mounted on the upper swing body 2. 5 and a work (excavation) attachment 9 comprising hydraulic cylinders 6, 7, 8 for booms, arms, and buckets for driving them.

  FIG. 2 shows a block configuration of the drive / control system of the entire shovel.

  As shown in the figure, a hydraulic pump 11 is driven by an engine 10, and the discharge oil of the hydraulic cylinders 6 to 8 and the left and right traveling motors 12 and 13 that drive the lower traveling body 1 are supplied to control valves 14 (for each actuator). But is shown here as a single valve block).

  In addition, a generator 13 is connected to the engine 10 via a speed increasing mechanism 15, and electric power generated by the generator 13 is stored in the battery 15 via a controller 14 that controls voltage and current, It is added to the swing motor 17 via the inverter 16.

  As a result, the turning electric motor 17 rotates, and the rotational force is transmitted to the upper turning body 2 via the turning speed reduction mechanism 18 so that the turning body 2 turns left or right.

  Reference numeral 19 denotes a lever-type turning operation unit (for example, a potentiometer) as a turning operation means. When the operation is normal, a command is issued from the controller 20 to the inverter 16 based on an operation signal from the turning operation unit 19, and based on this command. Each control of acceleration, deceleration, and stop holding of the swing motor 17 is performed.

  Here, the turning electric motor 17 is controlled by an inverter at the time of turning acceleration and performs an electric motor action with at least one of the electric power of the generator and the battery 15, and is controlled by an inverter at the time of deceleration to perform an electric generator action, and generates electric power generated by regenerative power generation. Store in battery 15.

  Further, the turning electric motor 17 is provided with a mechanical brake 21 that generates a mechanical braking force.

  As shown in FIG. 3, the mechanical brake 21 is configured as a hydraulic negative brake that releases a braking force when hydraulic pressure is introduced from a brake hydraulic pressure source 22 via an electromagnetic switching valve 23. The turning operation is performed in the unlocked state.

  The configuration of the brake circuit A that controls the brake operation in an emergency will be described with reference to FIG.

  The swing motor 17 is a permanent magnet type motor that generates electric power by inertial rotation even when the power is cut off, and exerts an electric brake function by flowing the generated electric power through a braking resistor 24 provided outside the electric motor.

  The braking resistor 24 is branched and connected to the power supply line of the swing motor 17 via the rectifier circuit 25 and is energized when the normally closed contact 27 of the first relay 26 or the normally open contact 29 of the second relay 28 is turned on.

  Reference numeral 30 denotes a voltage detection circuit for detecting the generated voltage of the swing motor 17. The output of the circuit 30 is sent as a one input voltage Vi to a voltage comparison circuit 33 as speed detection means via a transformer 31 and a rectifier circuit 32. Are compared with the set value Vref.

  That is, the current flowing through the braking resistor 24 decreases in proportion to the decrease in the rotational speed of the swing motor 17 (upper swing body 2), and the output of the voltage detection circuit 30 also decreases accordingly. Thus, it can be determined whether or not the turning speed is equal to or lower than the set value. Specifically, a signal “L” is output when Vi ≧ Vref, and a signal “H” is output when Vi <Vref.

  The output side of the voltage comparison circuit 33 is connected to a logic circuit 37 as an output circuit including NOT, AND, and OR elements 34, 35, and 36, and the output of the voltage comparison circuit 33 is input to the NOT element 34. The

  The AND element 35 receives an output (“H” when normal, “L” when normal) from the watchdog transistor 38 that monitors the occurrence of abnormality of the controller 20, and an operation or deactivation command for the mechanical brake 21 from the controller 20. The output of the mechanical brake command output transistor 39 to be output (“L” at the time of operation command, “H” at the time of release command) is input, and each output of the NOT element 34 and this AND element 35 is input to the OR element 36.

  An amplification circuit 40 is connected to the output side of the OR element 36, and when the signal “H” is output from the OR element 36 (normal time), an operation release signal is output to the electromagnetic switching valve 23 via the amplification circuit 40. Is done.

  As a result, the switching valve 23 is switched from the brake operation position A on the left side of the drawing to the operation release position B on the right side, and the mechanical brake 21 is released.

  Table 1 is a logical value table for each item of the output of the mechanical brake command output transistor 39, the output of the watchdog transistor 38, the motor speed, and the mechanical brake operation, and the following operation is performed according to this logical value table.

  (I) When the output of the watchdog transistor 38 outputs a signal “H” indicating that the controller is normal, the output of the mechanical brake command output transistor 39 outputs a signal “H” indicating a mechanical brake operation release command. The OR output becomes “H” regardless of the motor speed, and the mechanical brake 21 remains released.

  (II) When the output of the watchdog transistor 38 outputs a signal “H” indicating that the controller is normal and the output of the mechanical brake command output transistor 39 outputs a signal “L” indicating a mechanical brake operation command, When the speed is faster than the set value, the OR output is “H” and the mechanical brake 21 is released. However, when the motor speed is slower than the set value, the OR output is “L” and the mechanical brake 21 is released. Is activated.

  (III) When an abnormality occurs in the controller 20 and the output of the watchdog transistor 38 becomes “L”, if the motor speed is higher than the set value regardless of the output state of the mechanical brake command output transistor 39, the OR output is “H” and the mechanical brake 21 is released, but when the motor speed is slower than the set value, the OR output becomes “L” and the mechanical brake 21 is activated.

  On the other hand, the relay contact 27 is turned off when the controller is normal and turned on when the controller is abnormal. The relay contact 29 is turned on by a signal from the controller 20 when the electric motor power is cut off.

That means
a) When an abnormality occurs in the controller 20 due to the interruption of the control power supply or the failure of the controller itself, the relay contact 27 is turned on.

  b) When the motor power supply is cut off due to a failure of the generator 13, etc., when the controller 20 is operating normally, the controller 20 detects this power cut-off by, for example, a voltage drop and activates the second relay 28. The relay contact 29 is turned on.

  c) When the motor power supply is cut off and an abnormality occurs in the controller 20, the relay contact 27 is turned on because the output of the watchdog transistor 38 shows an abnormality.

  As a result, in any case, an electric current flows through the braking resistor 24 and the electric brake operates, and the electric motor brakes the turning electric motor 17, and the mechanical brake 21 is activated when the electric motor speed falls below the set value.

  Due to the above action, as shown in FIG. 4, the electric brake action automatically decelerates in the event of an emergency, and the turning motor 17 (upper turning body 2) is stopped and held by the mechanical brake 21 at the end of the deceleration. .

  Here, the torque of the electric brake is determined by the value of the braking resistor 24, and is maximum at the start of deceleration from the maximum speed, and decreases as the turning speed (inertia rotation speed) decreases.

  It is desirable to set the maximum torque of the electric brake to a value substantially equal to the maximum motor braking torque during normal operation for the following reason.

  FIG. 5 shows the relationship between the time during emergency braking and the motor speed, and FIG. 6 shows the relationship between the time and the turning angle required to stop.

  When braking with the maximum motor torque at normal time, braking is performed with a constant torque and a constant acceleration, thereby exhibiting the characteristics of the straight line A in FIG. 5 and the curve A in FIG. 6 (efficiency is ignored).

  On the other hand, when the electric brake maximum torque is made equal to the normal motor maximum torque, the characteristics of curve B in FIG. 5 and curve B in FIG. 6 are shown, and the time required to stop and the braking distance (angle) are normal (i.e. , A).

  Therefore, when the characteristic of the curve C in FIG. 6 is targeted so that the braking distance is the same as that at the normal time, the electric brake maximum torque becomes about twice as large as that at the normal time. In this case, the torque burden on the swing motor 17 and the speed reduction mechanism 18 is also doubled, so that the problem of heat generation (proportional to the square of the current) due to the current flowing through the internal resistance of the motor 17 and the strength problem of the speed reduction mechanism 18 occur. To do.

  On the other hand, if the target curve D in FIG. 5 is set so that the braking time is equal to that in the normal state, the maximum electric brake torque is further increased, which is not practical.

  Further, when the electric brake maximum torque is set smaller than the normal motor maximum torque, a curve E in FIG. 5 is obtained. Although there is no problem with the heat generation of the electric motor 17 or the strength of the speed reduction mechanism 18, there is a problem in terms of safety because the time until the stop becomes very long and the braking angle becomes very large.

  From the above points, it is the most desirable choice to set the electric brake maximum torque in an emergency to a value equivalent to the motor maximum torque in a normal state and to operate the mechanical brake 21 when the turning speed becomes less than the set value. Become.

  The motor speed (turning speed) for starting the operation of the mechanical brake 21 is to reduce the thermal load of the brake 21 to prevent its breakage (or to avoid the enlargement for preventing damage as much as possible). It is set in consideration of the viewpoint of reducing the braking time and the braking distance, and usually the mechanical brake 21 is operated when the turning speed becomes sufficiently low (for example, about 50 rad / s) as shown in FIG. .

  Alternatively, the mechanical brake 21 may be operated when the speed becomes 0 or almost 0 by the electric brake. In this case, the electric brake mainly performs a braking action, and the mechanical brake 21 mainly performs a stop-holding action.

  By the way, in the above embodiment, the voltage detection circuit 30 in the electric brake circuit detects the terminal voltage of the braking resistor 24 as the speed, and the detected voltage is compared with the set value by the voltage comparison circuit 33 so that the turning speed is equal to or higher than the set value. The current flowing through the braking resistor 24 is detected, the detected current value is compared with the set current value, and the turning speed is equal to or higher than the set value. It may be configured to determine whether or not and perform the same control as described above.

  Further, the rotational speed of the turning motor 17 or the turning speed reduction mechanism 18 or the turning speed of the upper turning body 2 is directly detected by the speed sensor, and is compared with the set value by the controller 20 or another comparison unit. Also good. In this case, it is desirable to use a speed sensor that operates even when the power is down (for example, a tachometer).

  The mechanical brake 21 is not limited to the cylinder structure of the above embodiment, and a hydraulically driven or electrically driven disk brake or the like may be used.

1 is a schematic side view of an excavator to which the present invention is applied. It is a block block diagram which shows embodiment of this invention. It is a circuit diagram of the brake circuit in the same embodiment. It is a figure which shows the operation timing of an electric brake and a mechanical brake. It is a figure which shows the relationship between the maximum torque of an electric brake, the time of braking, and an electric motor speed with several patterns. It is a figure which shows the relationship between the maximum torque of an electric brake, the time of braking, and a turning angle with several patterns.

Explanation of symbols

2 Upper swing body 17 Swing motor 16 Inverter 20 constituting control means Same controller 21 Mechanical brake as hydraulically driven negative brake 23 Electromagnetic switching valve for controlling operation of mechanical brake A Electric brake circuit constituting control means 24 Braking resistor 33 Voltage comparison circuit as speed detection means

Claims (6)

  A permanent magnet type motor is used as a swing motor that drives the swing body to swing, and in an emergency, the electric brake action is performed by consuming electric power generated in the swing motor by inertial rotation by a braking resistor outside the motor. An emergency turning braking method for a work machine characterized in that the rotating body is braked and decelerated by the action and the mechanical brake is operated at the end of the deceleration.   A turning motor that drives the turning body to turn, a mechanical brake that mechanically brakes the turning motor, a control unit that controls the operation of the turning motor and the mechanical brake, and a speed detection unit that detects a turning speed. As the swing motor, a permanent magnet type motor that performs an electric brake action by consuming electric power generated by inertial rotation with a braking resistor outside the motor is used, and the control means has an electric brake action on the swing motor in an emergency. And the mechanical brake is operated based on a speed signal from the speed detection means when the turning speed of the turning body decreases below a set value due to the electric brake action. Emergency turning braking device for work machines.   As the mechanical brake, a hydraulic negative brake that releases the braking force when hydraulic pressure is introduced through the switching valve is used, and the control means is configured to control the operation of the switching valve. The emergency turning braking device for a work machine according to claim 2.   As a speed detection means, it has a comparison part that compares a voltage or current due to the power generation action of the swing motor and a set value, and is configured to operate a mechanical brake based on a comparison result of the comparison part The emergency turning braking device for a work machine according to claim 2 or 3.   4. The emergency turning braking device for a work machine according to claim 2, wherein a speed sensor for detecting a rotation speed of the turning electric motor or a speed reduction mechanism thereof is used as the speed detecting means.   6. The emergency of the working machine according to claim 2, wherein the maximum torque due to the electric brake action of the swing motor is set to a value substantially equal to the maximum motor braking torque during normal operation. Swing brake device.

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